1. Field of the Invention
This invention relates generally to agricultural cultivators and more particularly to multiple row, vehicle drawn cultivators used in the cultivation, fertilization and chemical application of sugar cane.
2. General Background
In most cases a three rows cultivator is simply towed behind a tractor while being raised and lowered by the tractor's hydraulic draw bar. However, this puts an enormous strain on the tractor's draw bar and limits the type and number of implements being towed. Vehicle drawn cultivators are widely used and well known within the art, especially for multiple row cultivators. Such apparatus generally includes an implement frame structure having several wheels and an attachment means or hitch for securing the implement frame structure to a motor vehicle such as a tractor. The apparatus also generally includes a method for raising and lowering the implements relative to the ground to control the amount of penetration of the ground by the implement and to hold the implement above ground level when necessary. This arrangement allows the weight of the frame and implements to be carried by the cultivator wheels rather than by the hydraulic draw bar of the tractor. Examples of the prior art are disclosed in the following patents; Pat. Nos. 3,672,701, 4,036,304, 4,211,288, 4,637,474, 5,346,019, 5,477,930, 5,524,712, and 5,535,832. As can be seen in these disclosures, almost without exception, the cultivators rely on plural wheels to support the implement frame and implements. They all provide some means for caming the wheels, thereby lifting the frame and its implements. These apparatus are generally implement dependent, therefore, generally configured for a specific type of implement rather than utilizing a common implement bar for attaching and positioning any type of implement. Although this arrangement has received wide acceptance in most agricultural applications, there are several disadvantages which are amplified due to special requirements of sugar cane farming. For example, sugar cane requires very high rows and deep furrows, thereby limiting the width of the wheels allowable in a single furrow and requiring high ground clearance. Further, large chemical tanks are normally carried on the tractor, due to their great weight, thereby hindering the visibility of the tractor driver, increasing ground penetration by the front steering wheels and hindering air circulation to the tractor's engine.
Therefore, it would be advantageous for the cane farmer to have a cultivator which utilizes a frame structure having no central axle, thereby allowing for deep furrows, only two wheels for straddling the row, a method for carrying large chemical tanks, and a method for raising and lowering the implement frame without lifting the chemical tanks.